Adding encoding of payload headers, currently defaults to existing behavior, not encoding

temporalio/bridge/worker.py

@@ -11,6 +11,7 @@
     Awaitable,
     Callable,
     List,
+    Mapping,
     Optional,
     Sequence,
     Set,
@@ -271,6 +272,35 @@ async def finalize_shutdown(self) -> None:
     )
 
 
+async def _apply_to_headers(
+    headers: Mapping[str, temporalio.api.common.v1.Payload],
+    cb: Callable[
+        [Sequence[temporalio.api.common.v1.Payload]],
+        Awaitable[List[temporalio.api.common.v1.Payload]],
+    ],
+) -> None:
+    """Apply API payload callback to headers."""
+    for payload in headers.values():
+        new_payload = (await cb([payload]))[0]
+        payload.CopyFrom(new_payload)
+
+
+async def _decode_headers(
+    headers: Mapping[str, temporalio.api.common.v1.Payload],
+    codec: temporalio.converter.PayloadCodec,
+) -> None:
+    """Decode headers with the given codec."""
+    return await _apply_to_headers(headers, codec.decode)
+
+
+async def _encode_headers(
+    headers: Mapping[str, temporalio.api.common.v1.Payload],
+    codec: temporalio.converter.PayloadCodec,
+) -> None:
+    """Encode headers with the given codec."""
+    return await _apply_to_headers(headers, codec.encode)
+
+
 async def _apply_to_payloads(
     payloads: PayloadContainer,
     cb: Callable[
@@ -336,11 +366,14 @@ async def _encode_payload(
 async def decode_activation(
     act: temporalio.bridge.proto.workflow_activation.WorkflowActivation,
     codec: temporalio.converter.PayloadCodec,
+    decode_headers: bool,
 ) -> None:
     """Decode the given activation with the codec."""
     for job in act.jobs:
         if job.HasField("query_workflow"):
             await _decode_payloads(job.query_workflow.arguments, codec)
+            if decode_headers:
+                await _decode_headers(job.query_workflow.headers, codec)
         elif job.HasField("resolve_activity"):
             if job.resolve_activity.result.HasField("cancelled"):
                 await codec.decode_failure(
@@ -385,8 +418,12 @@ async def decode_activation(
                 await codec.decode_failure(job.resolve_signal_external_workflow.failure)
         elif job.HasField("signal_workflow"):
             await _decode_payloads(job.signal_workflow.input, codec)
+            if decode_headers:
+                await _decode_headers(job.signal_workflow.headers, codec)
         elif job.HasField("initialize_workflow"):
             await _decode_payloads(job.initialize_workflow.arguments, codec)
+            if decode_headers:
+                await _decode_headers(job.initialize_workflow.headers, codec)
             if job.initialize_workflow.HasField("continued_failure"):
                 await codec.decode_failure(job.initialize_workflow.continued_failure)
             for val in job.initialize_workflow.memo.fields.values():
@@ -400,11 +437,14 @@ async def decode_activation(
                 val.data = new_payload.data
         elif job.HasField("do_update"):
             await _decode_payloads(job.do_update.input, codec)
+            if decode_headers:
+                await _decode_headers(job.do_update.headers, codec)
 
 
 async def encode_completion(
     comp: temporalio.bridge.proto.workflow_completion.WorkflowActivationCompletion,
     codec: temporalio.converter.PayloadCodec,
+    encode_headers: bool,
 ) -> None:
     """Recursively encode the given completion with the codec."""
     if comp.HasField("failed"):
@@ -420,6 +460,10 @@ async def encode_completion(
                 await _encode_payloads(
                     command.continue_as_new_workflow_execution.arguments, codec
                 )
+                if encode_headers:
+                    await _encode_headers(
+                        command.continue_as_new_workflow_execution.headers, codec
+                    )
                 for val in command.continue_as_new_workflow_execution.memo.values():
                     await _encode_payload(val, codec)
             elif command.HasField("fail_workflow_execution"):
@@ -435,16 +479,30 @@ async def encode_completion(
                     )
             elif command.HasField("schedule_activity"):
                 await _encode_payloads(command.schedule_activity.arguments, codec)
+                if encode_headers:
+                    await _encode_headers(command.schedule_activity.headers, codec)
             elif command.HasField("schedule_local_activity"):
                 await _encode_payloads(command.schedule_local_activity.arguments, codec)
+                if encode_headers:
+                    await _encode_headers(
+                        command.schedule_local_activity.headers, codec
+                    )
             elif command.HasField("signal_external_workflow_execution"):
                 await _encode_payloads(
                     command.signal_external_workflow_execution.args, codec
                 )
+                if encode_headers:
+                    await _encode_headers(
+                        command.signal_external_workflow_execution.headers, codec
+                    )
             elif command.HasField("start_child_workflow_execution"):
                 await _encode_payloads(
                     command.start_child_workflow_execution.input, codec
                 )
+                if encode_headers:
+                    await _encode_headers(
+                        command.start_child_workflow_execution.headers, codec
+                    )
                 for val in command.start_child_workflow_execution.memo.values():
                     await _encode_payload(val, codec)
             elif command.HasField("update_response"):

temporalio/client.py

@@ -27,6 +27,7 @@
     Mapping,
     Optional,
     Sequence,
+    Text,
     Tuple,
     Type,
     Union,
@@ -37,6 +38,7 @@
 import google.protobuf.duration_pb2
 import google.protobuf.json_format
 import google.protobuf.timestamp_pb2
+from google.protobuf.internal.containers import MessageMap
 from typing_extensions import Concatenate, Required, TypedDict
 
 import temporalio.api.common.v1
@@ -66,6 +68,7 @@
     TLSConfig,
 )
 
+from .common import HeaderCodecBehavior
 from .types import (
     AnyType,
     LocalReturnType,
@@ -116,6 +119,7 @@ async def connect(
         lazy: bool = False,
         runtime: Optional[temporalio.runtime.Runtime] = None,
         http_connect_proxy_config: Optional[HttpConnectProxyConfig] = None,
+        header_codec_behavior: Optional[HeaderCodecBehavior] = None,
     ) -> Client:
         """Connect to a Temporal server.
 
@@ -160,6 +164,7 @@ async def connect(
                 used for workers.
             runtime: The runtime for this client, or the default if unset.
             http_connect_proxy_config: Configuration for HTTP CONNECT proxy.
+            header_codec_behavior: Encoding behavior for headers sent by the client.
         """
         connect_config = temporalio.service.ConnectConfig(
             target_host=target_host,
@@ -179,6 +184,9 @@ async def connect(
             data_converter=data_converter,
             interceptors=interceptors,
             default_workflow_query_reject_condition=default_workflow_query_reject_condition,
+            header_codec_behavior=HeaderCodecBehavior.NO_CODEC
+            if header_codec_behavior is None
+            else header_codec_behavior,
         )
 
     def __init__(
@@ -191,6 +199,7 @@ def __init__(
         default_workflow_query_reject_condition: Optional[
             temporalio.common.QueryRejectCondition
         ] = None,
+        header_codec_behavior: HeaderCodecBehavior = HeaderCodecBehavior.NO_CODEC,
     ):
         """Create a Temporal client from a service client.
 
@@ -208,6 +217,7 @@ def __init__(
             data_converter=data_converter,
             interceptors=interceptors,
             default_workflow_query_reject_condition=default_workflow_query_reject_condition,
+            header_codec_behavior=header_codec_behavior,
         )
 
     def config(self) -> ClientConfig:
@@ -1491,6 +1501,7 @@ class ClientConfig(TypedDict, total=False):
     default_workflow_query_reject_condition: Required[
         Optional[temporalio.common.QueryRejectCondition]
     ]
+    header_codec_behavior: Required[HeaderCodecBehavior]
 
 
 class WorkflowHistoryEventFilterType(IntEnum):
@@ -3849,6 +3860,10 @@ class ScheduleActionStartWorkflow(ScheduleAction):
     priority: temporalio.common.Priority
 
     headers: Optional[Mapping[str, temporalio.api.common.v1.Payload]]
+    """
+    Headers may still be encoded by the payload codec if present.
+    """
+    _from_raw: bool
 
     @staticmethod
     def _from_proto(  # pyright: ignore
@@ -3975,6 +3990,7 @@ def __init__(
         """
         super().__init__()
         if raw_info:
+            self._from_raw = True
             # Ignore other fields
             self.workflow = raw_info.workflow_type.name
             self.args = raw_info.input.payloads if raw_info.input else []
@@ -4034,6 +4050,7 @@ def __init__(
                 else temporalio.common.Priority.default
             )
         else:
+            self._from_raw = False
             if not id:
                 raise ValueError("ID required")
             if not task_queue:
@@ -4057,7 +4074,7 @@ def __init__(
             self.memo = memo
             self.typed_search_attributes = typed_search_attributes
             self.untyped_search_attributes = untyped_search_attributes
-            self.headers = headers
+            self.headers = headers  # encode here
             self.static_summary = static_summary
             self.static_details = static_details
             self.priority = priority
@@ -4135,8 +4152,12 @@ async def _to_proto(
                 self.typed_search_attributes, action.start_workflow.search_attributes
             )
         if self.headers:
-            temporalio.common._apply_headers(
-                self.headers, action.start_workflow.header.fields
+            await _apply_headers(
+                self.headers,
+                action.start_workflow.header.fields,
+                client.config()["header_codec_behavior"] == HeaderCodecBehavior.CODEC
+                and not self._from_raw,
+                client.data_converter.payload_codec,
             )
         return action
 
@@ -5884,7 +5905,7 @@ async def _populate_start_workflow_execution_request(
         if input.start_delay is not None:
             req.workflow_start_delay.FromTimedelta(input.start_delay)
         if input.headers is not None:
-            temporalio.common._apply_headers(input.headers, req.header.fields)
+            await self._apply_headers(input.headers, req.header.fields)
         if input.priority is not None:
             req.priority.CopyFrom(input.priority._to_proto())
         if input.versioning_override is not None:
@@ -5970,7 +5991,7 @@ async def query_workflow(self, input: QueryWorkflowInput) -> Any:
                 await self._client.data_converter.encode(input.args)
             )
         if input.headers is not None:
-            temporalio.common._apply_headers(input.headers, req.query.header.fields)
+            await self._apply_headers(input.headers, req.query.header.fields)
         try:
             resp = await self._client.workflow_service.query_workflow(
                 req, retry=True, metadata=input.rpc_metadata, timeout=input.rpc_timeout
@@ -6016,7 +6037,7 @@ async def signal_workflow(self, input: SignalWorkflowInput) -> None:
                 await self._client.data_converter.encode(input.args)
             )
         if input.headers is not None:
-            temporalio.common._apply_headers(input.headers, req.header.fields)
+            await self._apply_headers(input.headers, req.header.fields)
         await self._client.workflow_service.signal_workflow_execution(
             req, retry=True, metadata=input.rpc_metadata, timeout=input.rpc_timeout
         )
@@ -6127,9 +6148,7 @@ async def _build_update_workflow_execution_request(
                 await self._client.data_converter.encode(input.args)
             )
         if input.headers is not None:
-            temporalio.common._apply_headers(
-                input.headers, req.request.input.header.fields
-            )
+            await self._apply_headers(input.headers, req.request.input.header.fields)
         return req
 
     async def start_update_with_start_workflow(
@@ -6685,6 +6704,33 @@ async def get_worker_task_reachability(
         )
         return WorkerTaskReachability._from_proto(resp)
 
+    async def _apply_headers(
+        self,
+        source: Optional[Mapping[str, temporalio.api.common.v1.Payload]],
+        dest: MessageMap[Text, temporalio.api.common.v1.Payload],
+    ) -> None:
+        await _apply_headers(
+            source,
+            dest,
+            self._client.config()["header_codec_behavior"] == HeaderCodecBehavior.CODEC,
+            self._client.data_converter.payload_codec,
+        )
+
+
+async def _apply_headers(
+    source: Optional[Mapping[str, temporalio.api.common.v1.Payload]],
+    dest: MessageMap[Text, temporalio.api.common.v1.Payload],
+    encode_headers: bool,
+    codec: Optional[temporalio.converter.PayloadCodec],
+) -> None:
+    if source is None:
+        return
+    if encode_headers and codec is not None:
+        for payload in source.values():
+            new_payload = (await codec.encode([payload]))[0]
+            payload.CopyFrom(new_payload)
+    temporalio.common._apply_headers(source, dest)
+
 
 def _history_from_json(
     history: Union[str, Dict[str, Any]],

temporalio/common.py

@@ -1230,3 +1230,14 @@ def _type_hints_from_func(
         # necessarily
         args.append(arg_hint)  # type: ignore
     return args, ret
+
+
+class HeaderCodecBehavior(IntEnum):
+    """Different ways to handle header encoding"""
+
+    NO_CODEC = 1
+    """Don't encode or decode any headers automatically"""
+    CODEC = 2
+    """Encode and decode all headers automatically"""
+    WORKFLOW_ONLY_CODEC = 3
+    """Only automatically encode and decode headers in workflow activation encoding and decoding."""

temporalio/worker/_activity.py

@@ -69,6 +69,7 @@ def __init__(
         data_converter: temporalio.converter.DataConverter,
         interceptors: Sequence[Interceptor],
         metric_meter: temporalio.common.MetricMeter,
+        encode_headers: bool,
     ) -> None:
         self._bridge_worker = bridge_worker
         self._task_queue = task_queue
@@ -78,6 +79,7 @@ def __init__(
         self._data_converter = data_converter
         self._interceptors = interceptors
         self._metric_meter = metric_meter
+        self._encode_headers = encode_headers
         self._fail_worker_exception_queue: asyncio.Queue[Exception] = asyncio.Queue()
         # Lazily created on first activity
         self._worker_shutdown_event: Optional[temporalio.activity._CompositeEvent] = (
@@ -542,6 +544,14 @@ async def _execute_activity(
             workflow_type=start.workflow_type,
             priority=temporalio.common.Priority._from_proto(start.priority),
         )
+
+        if self._encode_headers and self._data_converter.payload_codec is not None:
+            for payload in start.header_fields.values():
+                new_payload = (
+                    await self._data_converter.payload_codec.decode([payload])
+                )[0]
+                payload.CopyFrom(new_payload)
+
         running_activity.info = info
         input = ExecuteActivityInput(
             fn=activity_def.fn,